Turbine blade staking pin

ABSTRACT

A staking pin for a gas turbine engine is disclosed. The staking pin may include a solid portion extending part of a length of the staking pin, and a hollow portion extending an additional part of the length of the staking pin. The staking pin may be constructed of Alloy X material having an average grain diameter of between about 0.0449 and 0.1270 mm.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/680,669, filed Aug. 7, 2012, which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

The present disclosure is directed to a pin of a gas turbine engine(GTE) and, more particularly, to a staking pin for staking a turbineblade in a turbine rotor disk of the GTE.

BACKGROUND

GTEs produce power by extracting energy from a flow of hot gas producedby combustion of fuel in a stream of compressed air. In general, turbineengines have an upstream air compressor coupled to a downstream turbinewith a combustion chamber (“combustor”) in between. Energy is releasedwhen a mixture of compressed air and fuel is burned in the combustor.The resulting hot gases are directed over blades of the turbine to spinthe turbine and produce mechanical power.

Turbine blades and other components of GTEs are subject to hightemperatures and high. local stresses during operation. Due to rotationof a turbine rotor disk supporting the turbine blades, the turbineblades experience a centrifugal force, and therefore must be retainedwithin the rotor disk. While a turbine blade root, for example adovetail, can facilitate retention of the turbine blade, other oradditional means to retain the turbine blade can be employed.

U.S. Pat. No. 3,165,294 (“the '294 patent”) describes a lockingarrangement for holding blades of a rotor assembly in a fluid flowmachine. According to the '294 patent, a rotor drum is provided with aplurality of axially spaced circumferentially extending slots. Aradially extending threaded or tapped hole is provided for a plug to bereceived therein. A blade having a root and a passage is positioned inthe slot, and a plug is disposed in the passage. The blade is thus heldagainst radial movement relative to the rotor drum, and the plug alsoholds an entire row of abutting blade roots against circumferentialmovement in the slot. The '294 patent further notes that during rotationof the rotor drum, centrifugal force urges the plug out of the threadedor tapped hole and into a locking direction.

SUMMARY

In one aspect, a staking pin for a gas turbine engine is disclosed. Thestaking pin may include a solid portion extending part of a length ofthe staking pin, and a hollow portion extending an additional part ofthe length of the staking pin. The staking pin may be constructed ofAlloy X material having an average grain diameter of between about0.0449 and 0.1270 mm.

In another aspect, a gas turbine engine is disclosed. The gas turbineengine may include a compressor system, a combustor system, and aturbine system. The turbine system may include at least one turbinerotor disk and a plurality of turbine blades each retained in theturbine rotor disk. At least one of the turbine blades may be retainedin the turbine rotor disk by a staking pin constructed of Alloy Xmaterial having an average grain diameter of between about 0.0449 and0.1270 mm, and extending through a portion of the at least one turbineblade

In yet another aspect, a staking pin for a gas turbine engine isdisclosed. The staking pin may include a solid portion extending part ofa length of the staking pin, and a hollow cylindrical portion includinga hole extending an additional part of the length of the staking pin.The cylindrical portion may have a wall thickness of about 1 mm, and thestaking pin may be constructed of Alloy X material having an averagegrain diameter of between about 0.0449 and 0.1270 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an exemplary disclosed GTE;

FIG. 2 is a cross-sectional view of a portion of the GTE of FIG. 1 withone embodiment of a staking pin according to the present disclosure;

FIG. 3 is a magnified view of encircled portion “3” in FIG. 2;

FIG. 4 is a top view of one of the turbine blades of FIG. 2;

FIG. 5 is a side view of the staking pin shown in FIG. 2;

FIG. 6 is an end view of the staking pin of FIG. 5; and

FIG. 7 is a magnified view of a portion of a surface of the staking pinof FIG. 2 showing one embodiment of the microstructure of the pin.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary gas turbine engine (GTE) 100. GTE 100may have, among other systems, a compressor system 10, a combustorsystem 20, a turbine system 70, and an exhaust system 90 arranged alongan engine axis 98. Compressor system 10 compresses air and delivers thecompressed air to an enclosure of combustor system 20. The compressedair is then directed from the enclosure into a combustor 50. Liquid orgaseous fuel may be directed into the combustor 50 through fuelinjectors 30. The fuel burns in combustor 50 to produce combustion gasesat high pressure and temperature. These combustion gases are used in theturbine system 70 to produce mechanical power. The turbine system 70 mayfurther include a plurality of turbine blades 72 installed on turbinerotor disks 76 (FIGS. 2 and 3). Additionally, the turbine system 70 caninclude a plurality of turbine nozzles as part of a series of turbinestators (not shown). The turbine blades 72, rotor disks 76, nozzles, andstators can be included in a series of turbine stages, for example, afirst stage 73, a second stage 74, and a third stage 75. Although onlythree stages 73, 74, 75 are illustrated in FIG. 1, more or fewer turbinestages may make up part of the turbine system 70. In operation, theturbine system 70 extracts energy from the combustion gases and directsthe exhaust gases through exhaust system 90.

FIG. 2 is a cross-sectional view of a portion of the turbine system 70shown in FIG. 1. Specifically, FIG. 2 shows a plurality of the turbineblades 72 installed on a turbine rotor disk 76 of one stage of theturbine system 70. Each turbine blade 72 includes a platform 12 and aroot 14 to be received in a correspondingly shaped cutout in the rotordisk 76. As shown in FIG. 2, the root 14 may be configured as adovetail; however, other root shapes and corresponding cutouts can beprovided for each turbine blade 72 and rotor disk 76, respectively. Eachroot 14 is received and supported between rotor disk posts 16 of therotor disk 76. It should be noted that FIG. 2 shows spaces between therotor disk 76 and the roots 14 and platforms 12 for illustrationpurposes only. While these spaces may exist in the turbine system 70,the rotor disk 76 may be in direct contact with one or more surfaces ofthe root 14 and/or platform 12 of one or more of the turbine blades 72.The rotor disk 76 includes slots 34 that may be formed in each rotordisk post 16. In some instances, the slots 34 extends circumferentiallyaround an outer diameter of the rotor disk 76, such that the “slots” 34may be referred to as a single slot 34. In other instances, however, theslots 34 may be formed so as to extend in an axial direction (i.e.parallel to the engine axis 98 and the flow of gas in the flow path 18)in each disk post 16. The slots 34 may also be referred to herein aschannels, rotor disk grooves, or the like.

As shown in FIG. 2, each turbine blade 72 may include a hole 36 throughthe platform 12. This hole 36 may be configured to align with the slot34 such that the hole 36 and the slot 34 can receive a staking pin 22.As described in more detail below, the staking pin 22 can be installedthrough the hole 36 and into the slot 34. The staking pin 22 may also bereferred to herein as either a locking pin, a retaining pin, or thelike.

FIG. 3 is a magnified view of the encircled portion “3” in FIG. 2. FIG.3 shows the staking pin 22 installed through the hole 36 and into theslot 34 so as to secure the turbine blade 72 to the rotor disk 16. Inthe installed state shown in FIG. 3, the portion of the staking pin 22disposed in the slot 34 exhibits what can be referred to as a flared ormushroom shape. That is, the portion of the staking pin 22 in the slot34 extends beyond the edges of the hole 36 under part of the platform12. Although FIG. 3 shows the portion of the staking pin 22 disposed inthe slot 34 being flared or mushroomed in a substantially uniformmanner, this may not always be the case. For example, the portion of thestaking pin 22 disposed in the slot 34 may deform in a non-uniformmanner, such that parts of a wall of a hollow cylindrical portion aredeformed more or less than other parts of the wall. In some instances,the portion of the staking pin 22 disposed in the slot 34 may have awidth substantially equal to a width 210 of the slot 34, which may begreater than a width of the portion of the staking pin 22 extendingthrough the hole 36 of the platform 12. Although not illustrated in FIG.2 or 3, in an installed state, the staking pin 22 may abut the sides ofthe slot 34 defining the width 210, such that the staking pin 22substantially spans the distance between the sides of the slot 34. FIG.3 also shows a depth 220 of the slot 34 extending into the disk post 16.

In the installed state, the staking pin 22 may protrude from theplatform 12 and into the flow path 18 by a protrusion distance 200. Theprotrusion distance 200 may be between about 0.254 mm to about 0.762 mm(about 0.010 inches to about 0.030 inches). In some instances, theprotrusion distance 200 may be less than about 0.508 mm (about 0.020inches). For example, the protrusion distance 200 may be about 0.381 mm(about 0.015 inches). In other instances, it may be possible to installthe staking pin 22 so as to be flush with the platform 12, such that thestaking pin 22 does not extend into the flow path 18.

FIG. 4 illustrates a top view of a turbine blade 72 according to thepresent application. As shown in FIG. 4, the platform 12 may be shapedas a parallelogram, for example, a rectangle or a rhomboid. The platform12 may include a first edge 24, a second edge 26, a third edge 28, and afourth edge 32, wherein the second edge 26 and the fourth edge 32 maydefine a length 300 of the platform 12, and wherein the first edge 24and the third edge 28 may define a width 306 of the platform 12. Thelength 300 may be between about 25.4 and 38.1 mm (about 1.0 and 1.5inches), and the width 306 may be between about 12.7 and 25.4 mm (about0.5 and 1.0 inches). In some instances, however, the length 300 and/orwidth 306 may have different values.

FIG. 4 shows the hole 36 having the staking pin 22 disposed therein.FIG. 4 shows the hole 36 positioned on a pressure side 38 of the turbineblade 72. In some embodiments, however, the hole 36 may be positioned ona suction side 40 of the turbine blade 72. In some instances, on eitherthe pressure side 38 or the suction side 40, the hole 36 may be locatedhalfway between the first edge 24 and the third edge 28. That is, thehole 36 may be located at a distance 302 from edge 24 that issubstantially equal to one-half the length 300 of the platform 12.Additionally, the hole 36 may be offset from one edge of the platform12, for example, the second edge 26, by a distance 304, in someembodiments, the distance 304 may be substantially equal to aboutone-fourth the width 306.

FIG. 5 shows a side view of the staking pin 22 prior to installation.The staking pin 22 has a length 400, also referred to as a total lengthor an overall length, and an outer diameter 404. Additionally, thestaking pin 22 may include the hollow cylindrical portion forming anopen end of the staking pin 22, wherein the cylindrical portion may havea length 406 that is less than the total pin length 400. Thiscylindrical portion may define a hollow interior portion of the stakingpin 22 having an inner diameter 402, and a tapered portion 410. Asdiscussed below, the length 406 may be greater than the depth 220 of theslot 34 in the rotor disk 76. FIG. 6 shows a cross-sectional view of thecylindrical portion of the staking pin 22 along lines 6-6 in FIG. 5. Thecylindrical portion may have a wall thickness 408, which is thedifference between the outer diameter 404 and the inner diameter 402.The hollow interior portion is a blind hole that may be referred toherein as a staking pin hole 42, and the length 406 may be referred toas a staking pin hole depth. The staking pin hole 42 may be formed viadrilling into the material forming the staking pin 22. The length of thestaking pin 22 that is not defined by the cylindrical portion may besolid and thus referred to herein as a solid portion of the staking pin22. The cylindrical portion may also be referred to herein as adeforming portion, a crumpling portion, a mushrooming portion, acrushing portion, or the like, because the cylindrical portion may be.configured to deform within the slot 34 during installation, asdescribed in more detail below. For example, when the staking pin 22 isinstalled in the turbine system 70 so as to hold a turbine blade 72 inthe turbine rotor disk 76, the outer diameter of the staking pin 22 inthe slot 34 may be greater than the outer diameter of the staking pin 22extending through the hole 36 in the turbine blade platform 12.

The dimensions of the staking pin 22 may have various values. In someinstances, the length 400 may be between about 5.000 and 6.000 mm(between about 0.197 and 0.236 inches), for example, about 5.969 mm(about 0.235 inches). The length 406 of the cylindrical portion may beless than or equal to about half the length 400. For instance, thelength 406 may be between about 2.000 and 3.000 mm (between about 0.079and 0.118 inches), for example, about 2.500 mm (about 0.098 inches).That is, the ratio of the length 400 to the length 406 may be, forexample, about 3 to 1, about 2 to 1, or, in some instances, about 2.4to 1. Additionally, the outer diameter 404 may be between about 3.000and 3.500 mm (between about 0.118 and 0.138 inches), for example, about3.162 mm (about 0.125). The inner diameter 402 may be about betweenabout 2.000 and 2.500 mm (between about 0.079 and 0.098 inches), forexample, about 2.108 mm (about 0.083 inches), or about 2.159 mm (about0.085 inches). Based on these dimensions, the thickness 408 may bebetween about 0.500 and 1.500 mm (about 0.020 to 0.059 inches),inclusive, or about 1.0 mm (about 0.039 inches). These values of thevarious pin dimensions are only examples, as other values may be used.

The staking pin 22 may be constructed from Alloy X material. Alloy X isa wrought nickel based superalloy, which exhibits both heat andoxidation resistance. For instance, a component such as a staking pinmade of Alloy X may be oxidation resistant to a temperature of 1,200° C.(2,200° F.); however, oxidation resistance to other temperature valuesmay be possible. Additionally, Alloy X may exhibit high yield andultimate tensile strengths, such that a minimum ultimate tensilestrength (UTS) may be about 655 MPa (about 95 ksi), and a minimum yieldstrength (YS) may be about 240 MPa (about 35 ksi) at GTE operatingtemperatures. The Alloy X material used to construct the staking pin 22may be provided as a bar, sheet, wire, or any other form. In someinstances, the staking pin 22 may be machined from either a wrought orcast form of Alloy X. In other instances, the staking pin 22 may be cutfrom Alloy X weld wire having a diameter substantially equal to theouter diameter 404. A segment of Alloy X material may be formed into acylindrical shape like that shown in FIG. 5, and a blind hole, such asstaking pin hole 42, may then be formed (e.g., drilled) into one end ofthe material to create the cylindrical portion of the staking pin 22.

FIG. 7 provides a magnified view of a portion of a surface of thestaking pin 22 of FIG. 2 showing one embodiment of the microstructure ofthe pin 22. The microstructure of the staking pin 22 may include grains55. When the staking pm 22 is constructed of Alloy X material, themicrostructure of the staking pin 22 may exhibit a specific grain size,which can influence the physical properties (e.g. oxidation resistance,corrosion resistance, strength, and temperature behavior) of the pin 22.The grain size may be referred to as an average diameter of one of thegrains 55. The grain size may also be referred to as a number “N,” whereN equals the number of grains 55 per square inch measured at amagnification of one-hundred times. For a larger N value, the grain sizeis smaller, and the material (e.g. Alloy X) may be referred to as being“fine”. For a smaller N value, such as N=4, the grain size is larger,and thus the material may be referred to as being “course.” FIG. 7 showsone embodiment of the microstructure of the staking pin 22 having agrain size of about N=16, which may correspond to an average graindiameter of about 0.1000 mm (about 0.0039 inches). In some instances,the staking pin 22 may be made from a material, such as Alloy X, havinga grain size N between 32 and 4, which may correspond to an averagegrain diameter between about 0.0449 and 0.1270 mm (about 0.0018 and0.0050 inches), respectively. In some cases, for example, the grains 55may have an average grain diameter of between about 0.0449 and 0.0750 mm(about 0.0018 and 0.0030 inches). If the Alloy X from which the stakingpin 22 is made is annealed, for example, the microstructure may exhibitlarger grain sizes around outer edges of the pin 22. Thus, annealing mayresult in grain sizes around the outer edges of the pin 22 having an Nvalue of approximately 4. Additionally, the annealing process may resultin non-uniform grain sizes in the pin 22, such that sections of the pin22 may have one grain size, while other sections of the pin 22 may haveanother grain size. For example, some sections of staking pin 22 mayhave a grain size of N=4, while other sections of staking pin 22 mayhave a grain size of N=8, which may correspond to an average graindiameter of about 0.0750 mm (about 0.0030 inches). Furthermore,different annealing temperatures can produce different grain sizes. Forinstance, if the Alloy X material is annealed at a temperature greaterthan about 1,093° C. (2,000° F.), the annealing process may producegrain sizes of for example, N=16 or N=32. If, however, the Alloy X fromwhich the staking pin 22 is made is not annealed, the pin 22 may, forexample, exhibit uniform grain sizes in the range of N=4 to N=6. Thesizes (e.g., the average diameters) and shapes of the grains 55 are notlimited to the examples discussed above and shown in the drawings.

To install the turbine blade 72 in the turbine system 70, the root 14 ofthe turbine blade 72 is inserted into a slot 34 of the turbine rotordisk 76 between adjacent disk posts 16. In this position, the hole 36 inthe platform 12 of the turbine blade 72 is aligned with the slot 34. Inorder to secure the turbine blade 72 on the turbine rotor disk 76, thestaking pin 22 is positioned above the hole 36 such that the cylindricalportion of the staking pin 22 is adjacent to or in contact with the hole36. The staking pin 22 is then pushed or struck, for example, at an endof the staking pin 22 opposite the staking pin hole 42, to push thestaking pin 22 through the hole 36 and into the slot 34 of the turbinerotor disk 76. The staking pin 22 may be struck manually with a hammer,or manually or automatically with any other instrument. As shown inFIGS. 2 and 3, the cylindrical portion of the staking pin 22 deforms or“mushrooms” within the slot 34 during installation, such thatcylindrical portion of the staking pin 22 in slot 34 expands to extendunder the platform 12. In the installed state, the expanded portion ofthe staking pin 22 may abut the walls of the slot 34 so as tosubstantially span the distance between the sides of the slot 34. Asdescribed herein, although FIG. 3 illustrates the staking pin 22 in aninstalled state having a substantially uniformly “mushroomed” portionwithin the slot 34, the cylindrical portion of the staking pin 22 may becrushed or mushroomed during installation in a non-uniform manner. Forexample, when the pin 22 is installed, part of the wall of thecylindrical portion may contact a wall of the slot 34, while anotherpart of the wall of the cylindrical portion may not be in contact with awall of the slot 34. Additionally, part of the wall of the cylindricalportion of the pin 22 may be bent at an angle that differs from theangle at which another part of the wall of the cylindrical portion isbent. As shown in FIGS. 5 and 6, prior to installation, the staking pin22 may have a constant outer diameter 404 along its entire length 400.Providing the staking pin hole 42 to form the cylindrical portion allowsfor the “mushrooming” of the staking pin 22 within the slot 34 to securethe staking pin 22 in the slot 34. Once secured in the slot 34, thestaking pin 22 prevents forward and aft movement of the turbine blade 72during operation of the GTE 100. Thus, when the staking pin 22 isinstalled, the outer diameter of the cylindrical portion disposed in theslot 34 may be greater than the initial outer diameter 404 prior toinstallation. Although FIGS. 2 and 3 show a uniform outer diameter ofthe portion of the staking pin 22 disposed in the slot 34, this outerdiameter is not necessarily uniform, and may vary along the length 406of the staking pin 22.

In some circumstances, after the staking pin 22 is installed, a turbineblade 72 or staking pin 22 removal or “de-staking” operation may also beperformed. A de-staking operation may be performed, for example, at theend of a predetermined service life, or if a problem with the turbineblade 72 is discovered during an inspection. To de-stake a pin 22, aninstrument, such as a metallic block, may be used to strike a portion ofthe staking pin 22 protruding from a surface of the turbine bladeplatform 12. Doing so may shear the staking pin 22 at a desiredlocation, for example, at a location that is flush with the surface ofthe platform 12. After the staking pin 22 is successfully sheared, anyremaining portions of the pin 22 may be removed from the turbine blade72 to complete the de-staking operation. In some instances, a newturbine blade 72 having a new, unused staking pin 22 can then beprovided. In other instances, however, a new staking pin 22 may beinstalled in a previously used turbine blade 72 in place of a de-stakedpin 22.

INDUSTRIAL APPLICABILITY

The above-disclosed staking pin system can be installed in an apparatusexperiencing high temperatures and stresses, such as a GTE. The stakingpin system may be installed in the combustor system, any stage of theturbine system, or the compressor system, including the stators. Inaddition, While being described for use in a GTE, the staking pin can beused generally in applications or industries requiring retention ofcomponents subject to, for example, a centrifugal force.

The GTE 100 produces power by extracting energy from a flow of hot gasproduced by combustion of fuel in a stream of compressed fluid, forexample air, from the compressor system 10. Energy is released when amixture of the compressed air and fuel is burned in the combustor system20. The fuel injectors 30 direct a liquid or gaseous fuel into thecombustor system 20 for combustion. The resulting hot gases are directedthrough the turbine system 70, past the stages 73, 74, 75, over statorvanes and the turbine blades, to spin the turbine blades 72 and rotors76 and produce mechanical power. Turbine blades 72 rotating within theturbine system 70 may each include a staking pin 22 disposed through theplatform 12 and into the slot 34 of the turbine rotor disk 76.

During turbine operation, the turbine blades 72 may experience highstresses. Turbine blade failures should be prevented as they may damagea GTE, and cause inconvenient and unscheduled shutdowns to repair and/orreplace damaged GTE components. If turbine blade staking pins are used,depending on their design, the staking pins may oxidize and fail as aresult of crack formation in the pin. As GTEs continue to operate athigher temperatures, there is a need for oxidation-resistant components,such as staking pins, in order to prevent failures and prematureshut-downs. Additionally, GTE components may experience corrosion dueto, for example, salt or sulfur, leading to failure due to crackformation.

The staking pin 22 according to the present description may providecertain advantages. For example, the material from which the staking pin22 may be made, i.e., Alloy X, in combination with the microstructureand pin dimensions described above, provide an oxidation-resistantstaking pin 22 that may avoid premature degradation after being exposedto the operating temperatures and conditions of the GTE 100. By usingthe staking pin 22 described in the instant application, the risk of GTEfailure and/or having to prematurely replace one of the turbine bladescan be reduced.

As described above, Alloy X is a high-strength wrought nickel basedsuperalloy. Due to its high strength, the staking pin 22 is designed soas to prevent significant protrusion of the staking pin 22 from thesurface of the platform 12 and into the flow path 18 when the stakingpin 22 is installed. Specifically, in some instances, the inner diameter402 of the staking pin hole 42 is such that the wall thickness 408 ofthe cylindrical portion is sufficiently thin to enable excellentdeformation, or “mushrooming,” of the pin 22 in the slot 34 duringinstallation. Mushrooming in the slot 34 beneath the platform 12 mayprevent the staking pin 22 from “backing out” of the hole 36 in theturbine blade platform 12 by locking the pin 22 in the hole 36. This, inturn, can secure the turbine blade 72 and prevent it from migrating ineither a forward or aft direction. This may reduce a risk of damage tocomponents, such as the turbine rotor 76 and/or turbine nozzles, in theturbine system 70 of the GTE 100. Either separately or in combinationwith providing a thin wall in the cylindrical portion of the staking pin22, the overall length 400 of the pin 22 may be relatively short tolimit protrusion of the pin 22 from the surface of the platform 12 whenthe pin 22 is installed.

In addition to being oxidation-resistant, the staking pin 22 made fromAlloy X material is both corrosion and heat resistant, and durable suchthat the staking pin 22 may withstand the stresses of GTE operation. Astaking pin 22 made from Alloy X may also exhibit desirable creepperformance to prevent failure due to creep. That is, the staking pin 22described herein may have less of a tendency than a staking pin made ofanother material to permanently deform under the influence of stresses,such as high temperatures and loads, during operation. Additionally, theAlloy X from which the pin 22 may be made can be inexpensive and readilyavailable as weld wire having an outer diameter that may be acceptablefor the staking pins 22, thereby reducing the time and expense ofmanufacturing the staking pins 22.

Thus, the disclosed configurations of staking pin 22 may reduce theincidence of damage to staking pin 22, such as damage resulting fromcracking due to oxidation. The staking pin 22 may be stable under GTEoperating stresses, such that cracking, even in the cylindrical portionat the staking pin hole 42 where cracking may be expected to initiate,can be prevented. Furthermore, the staking pin 22 described herein maylast at least as long as the turbine blade 72 in which it is installed.Therefore, unnecessary GTE shutdowns can be avoided, as can possibledamage, such as cracking, to the turbine rotor disk post 16 due toremoval of a turbine blade 72 whose staking pin prematurely failed.

Additionally, regarding the de-staking operation, using the staking pins22 described herein enables a relatively simple de-staking operation.While the staking pins 22 securely hold the turbine blades 72 in placeduring operation, if de-staking is necessary, a brittle failure mode ofthe staking pins 22 may allow for clean shearing of the pins 22 duringde-staking without damaging either the turbine rotor disk 76 or turbineblades 72. For example, the staking pins 22 may be broken or sheared ata location that is flush with a surface of the platform 12. The materialfrom which the pin 22 is made, for example, Alloy X, the microstructureof the pin 22 as described herein, and/or the dimensions of the pin 22,can contribute to the brittle failure mode of the staking pins 22 thatallows for clean shearing during de-staking.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed apparatus andmethod. Other embodiments will be apparent to those skilled in the artfrom consideration of the specification and practice of the disclosedsystem and method. It is intended that the specification and examples beconsidered as exemplary only, with a true scope being indicated by thefollowing claims and their equivalents.

What is claimed is:
 1. A staking pin for a gas turbine engine,comprising: a solid portion extending part of a length of the stakingpin; and a hollow portion extending an additional part of the length ofthe staking pin, wherein the staking pin is constructed of Alloy Xmaterial having an average grain diameter of between about 0.0449 and0.1270 mm.
 2. The staking pin of claim 1, wherein the hollow portion isa cylindrical portion including a hole extending the additional part ofthe length of the staking pin.
 3. The staking pin of claim 1, whereinthe hollow portion is less than half the length of the staking pin. 4.The staking pin of claim 1, wherein the hollow portion has a wallthickness of between about 0.500 and 1.500 mm.
 5. The staking pin ofclaim 1, wherein the hollow portion has a length of about 2.5 mm.
 6. Agas turbine engine, comprising: a compressor system; a combustor system;and a turbine system, wherein the turbine system comprises: at least oneturbine rotor disk; and a plurality of turbine blades each retained inthe turbine rotor disk, wherein at least one of the turbine blades isretained in the turbine rotor disk by a staking pin constructed of AlloyX material having an average grain diameter of between about 0.0449 and0,1270 mm and extending through a portion of the at least one turbineblade.
 7. The gas turbine engine of claim 6, wherein the staking pinextends into a slot formed in the turbine rotor disk.
 8. The gas turbineengine of claim 7, wherein the portion of the staking pin in the slothas a diameter greater than a diameter of a portion of the staking pinextending through the portion of the at least one turbine blade.
 9. Thegas turbine engine of claim 6, wherein the portion of the at least oneturbine blade is a platform, and wherein the staking pin protrudes froma surface of the platform.
 10. The gas turbine engine of claim 9,wherein the staking pin protrudes from a surface of the platform by adistance between about 0.254 mm and 0.762 mm.
 11. The gas turbine engineof claim 9, wherein the stacking pin protrudes from a surface of theplatform a distance of less than or equal to about 0.381 mm.
 12. The gasturbine engine of claim 9, wherein the staking pin extends through theplatform at a location substantially halfway between two opposite endsof the platform.
 13. The gas turbine engine of claim 6, wherein thestaking pin includes: a solid portion extending part of a length of thestaking pin; and a hollow portion extending from the solid portion andforming an open end of the staking pin, wherein the hollow portion isless than half the length of the staking pin.
 14. The gas turbine engineof claim 13, wherein the hollow portion is a cylindrical portionincluding a hole extending the additional part of the length of thestaking pin
 15. The gas turbine engine of claim 14, wherein thecylindrical portion has a wall thickness of between about 0.500 and1.500 mm.
 16. The gas turbine engine of claim 14, wherein thecylindrical portion has a length of about 2.5 mm.
 17. A staking pin fora gas turbine engine, comprising: a solid portion extending part of alength of the staking pin; and a hollow cylindrical portion including ahole extending an additional part of the length of the staking pin,wherein the cylindrical portion has a wall thickness of about 1 mm, andwherein the staking pin is constructed of Alloy X material having anaverage grain diameter of between about 0.0449 and 0.1270 mm.
 18. Thestaking pin of claim 17, wherein the staking pin has a total length ofabout 6 mm.
 19. The staking pin of claim 18, wherein the cylindricalportion has a length less than half the total length.
 20. The stakingpin of claim 17, Wherein the Alloy X material forming the staking pinhas non-uniform grain sizes wherein the grains have an average diameterof between about 0.0449 and 0.0750 mm.